The present invention relates to a carburetor for internal combustion engines with an acceleration pump whose pump chamber is connected to the float chamber by a suction duct containing a suction valve, and to the suction line section upstream of the throttle by a delivery duct containing a pressure valve and a calibrated injection opening. The acceleration pump has a displacement member which is actuated depending on the throttle position by means of a lever via a linkage.
Such devices are known, for example, from German Laid-Open Document No. 24 20 171, dated Jan. 2, 1975, where the injection is metered depending on the fuel temperature. However, with the known pumps it is impossible to adapt the acceleration quantity to the requirements of the engine and to the exhaust gas laws. During acceleration in the upper range, that is, with an acceleration based on a specific throttle opening, CO peak values are obtained when measuring the exhaust gases. This is due to the fact that the injected amount is too large. However, if the pump is adjusted so that the injected amount is reduced, it becomes too small for the lower range of throttle opening and the engine runs out of true.
Accordingly, it is an object of the present invention to provide a device which in the lower range of the throttle opening angle injects a larger adjustable volume than in the upper range.
Another object of the present invention is to provide an arrangement of the foregoing character which is substantially simple in construction and may be economically fabricated.
A further object of the present invention is to provide a carburetor, as described, which may be readily maintained in service and which has a substantially long operating life.